Chapter 53.1 - A community's interactions include competition, predation, herbivory, symbiosis, and disease. (Final check at 9:00 AM 12/11/10. Looks complete.)
Community – the collection of different species living close enough for potential interaction. Interspecific interactions – interactions that occur between different species living in a community. Interspecific competitions – competition between two species that use the same limited resource that can affect the survival and reproduction of both populations Competitive exclusion principle – principle that predicts that the less efficient competitor will be locally eliminated. Ecological niche – an organism’s role in an ecosystem.
A species’ fundamental niche is the niche potentially occupied by that species. It is the niche that the species’ would occupy if there were no other species in its environment. A realized niche is what it actually occupies in a particular environment and is affected by other organisms in its environment. Resource partitioning is the modification of one species’ niche and the two species can co-exist without both dying. An example of resource partitioning is the seven species of Dominican Republic lizards that live closely together and feed on insects but have a different competition for food because of where they sit or perch like in the shade or the sun. Character displacement is the tendency for characteristics to be more differing in closely related species when their communities when their environments overlap than when their environments are not connected at all. An example of this is closely birds living in the same general geographic area but they have a varying beak size
Interspecific reactions: Predation= refers to a +/- interaction between species in which one species (+) kills and eats the other (-). Herbivory- refers to a +/- interaction in which a herbivore (+) eats parts of a plant or algae (-). Cattle eat grass. Parasitism- refers to +/- interaction between a parasite (+) that derives its nutrients from a host (-) that is harmed in the process. Heart worms in a pet. Mutualism- is a +/+ interaction that benefits both species. Acacia trees that provide shelter and food for the ants, while the ants attach that anything that touches the tree. Commensalism- interaction between species that benefits one of the species but neither harms nor helps the other(+0). Birds that follow predators and eat the food after predators kill it. Cryptic coloration- animal blends into its environment so it is more difficult for the predator to see it. Aposematic coloration- bright colors on an animal that has chemicals it uses to ward off a predator In Batesian mimicry, a relatively harmless animal mimics the appearance of a harmful animal. Example: hawk moth larva that puffs their head up and his like a snake when there is a predator. Mullerian mimicry- two or more harmful species resemble each other. Predators won’t attack because there is a greater number of harmful prey, the more they will avoid those colors. An example is the cuckoo bee and the yellow jacket. Endoparasitism- parasite inside its host Ectoparasitism- parasite on outside of host, like ticks Some parasites can affect the behavior of their first host so it is easier to move to their second host. Parasites can effect survival, reproduction, and density of their host population in direct or indirect ways. Like a tick that is on a moose, it makes the moose weaker and soon die from Preditation of other animals. Pathogens- disease-causing agents that can be bacteria, viruses, or protists, that are much smaller than parasites and inflict lethal harm. Coevolution- two interacting species in which a change in one species acts as a force on another species whose adaptation to this then affects the first species. An example is the gene-for-gene recognition between plant species and a species of an invading pathogen [disease causing agent]. Coevolutione can be confused, like with aposematic color of various tree frogs. They pose a warning for many predators and not just one, therefore it isn’t coevolution.
Species richness is the total number of different species in a community. Relative abundance is the proportion each species represents of the total individuals in the community.
Figure 53.11 shows the difference between relative abundance and species richness.
A food chain is the transfer of food energy up the trophic levels from its source in plants and other photosynthetic organisms through herbivores to carnivores and eventually to decomposers. A food web is the interconnected feeding relationships in an ecosystem. A food web shows all species involved in the feeding. A food chain shows only one species for each level of the chain. The energetic hypothesis suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain.
The dynamic stability hypothesis proposes that long food chains are less stable than short chains because of population fluctuations.
Dominant species are the species in a community that are the most abundant or that collectively have the highest biomass. Biomass is the total mass of all individuals in a population. Keystone species are species that are not abundant in a community. Invasive species are species that are generally introduced by humans that take hold outside their native range. Bottom-up model when an increase in mineral nutrients increase the biomass in trophic levels like vegetation, herbivores, and predators. Top-down model when predation controls community organization with +/- effects all the way down to trophic levels [trophic cascade model]
Community – the collection of different species living close enough for potential interaction.
Interspecific interactions – interactions that occur between different species living in a community.
Interspecific competitions – competition between two species that use the same limited resource that can affect the survival and reproduction of both populations
Competitive exclusion principle – principle that predicts that the less efficient competitor will be locally eliminated.
Ecological niche – an organism’s role in an ecosystem.
A species’ fundamental niche is the niche potentially occupied by that species. It is the niche that the species’ would occupy if there were no other species in its environment. A realized niche is what it actually occupies in a particular environment and is affected by other organisms in its environment.
Resource partitioning is the modification of one species’ niche and the two species can co-exist without both dying. An example of resource partitioning is the seven species of Dominican Republic lizards that live closely together and feed on insects but have a different competition for food because of where they sit or perch like in the shade or the sun. Character displacement is the tendency for characteristics to be more differing in closely related species when their communities when their environments overlap than when their environments are not connected at all. An example of this is closely birds living in the same general geographic area but they have a varying beak size
Interspecific reactions:
Predation= refers to a +/- interaction between species in which one species (+) kills and eats the other (-).
Herbivory- refers to a +/- interaction in which a herbivore (+) eats parts of a plant or algae (-). Cattle eat grass.
Parasitism- refers to +/- interaction between a parasite (+) that derives its nutrients from a host (-) that is harmed in the process. Heart worms in a pet.
Mutualism- is a +/+ interaction that benefits both species. Acacia trees that provide shelter and food for the ants, while the ants attach that anything that touches the tree.
Commensalism- interaction between species that benefits one of the species but neither harms nor helps the other(+0). Birds that follow predators and eat the food after predators kill it.
Cryptic coloration- animal blends into its environment so it is more difficult for the predator to see it.
Aposematic coloration- bright colors on an animal that has chemicals it uses to ward off a predator
In Batesian mimicry, a relatively harmless animal mimics the appearance of a harmful animal.
Example: hawk moth larva that puffs their head up and his like a snake when there is a predator.
Mullerian mimicry- two or more harmful species resemble each other. Predators won’t attack because there is a greater number of harmful prey, the more they will avoid those colors. An example is the cuckoo bee and the yellow jacket.
Endoparasitism- parasite inside its host
Ectoparasitism- parasite on outside of host, like ticks
Some parasites can affect the behavior of their first host so it is easier to move to their second host. Parasites can effect survival, reproduction, and density of their host population in direct or indirect ways. Like a tick that is on a moose, it makes the moose weaker and soon die from Preditation of other animals.
Pathogens- disease-causing agents that can be bacteria, viruses, or protists, that are much smaller than parasites and inflict lethal harm.
Coevolution- two interacting species in which a change in one species acts as a force on another species whose adaptation to this then affects the first species. An example is the gene-for-gene recognition between plant species and a species of an invading pathogen [disease causing agent]. Coevolutione can be confused, like with aposematic color of various tree frogs. They pose a warning for many predators and not just one, therefore it isn’t coevolution.
Species richness is the total number of different species in a community. Relative abundance is the proportion each species represents of the total individuals in the community.
Figure 53.11 shows the difference between relative abundance and species richness.
A food chain is the transfer of food energy up the trophic levels from its source in plants and other photosynthetic organisms through herbivores to carnivores and eventually to decomposers. A food web is the interconnected feeding relationships in an ecosystem. A food web shows all species involved in the feeding. A food chain shows only one species for each level of the chain.
The energetic hypothesis suggests that the length of a food chain is limited by the inefficiency of energy transfer along the chain.
The dynamic stability hypothesis proposes that long food chains are less stable than short chains because of population fluctuations.
Dominant species are the species in a community that are the most abundant or that collectively have the highest biomass. Biomass is the total mass of all individuals in a population. Keystone species are species that are not abundant in a community.
Invasive species are species that are generally introduced by humans that take hold outside their native range.
Bottom-up model when an increase in mineral nutrients increase the biomass in trophic levels like vegetation, herbivores, and predators.
Top-down model when predation controls community organization with +/- effects all the way down to trophic levels [trophic cascade model]